The goalposts have moved! See your forum Post #10
You can edit the control points of the cubic curve to adjust the shape, for example:
Note the elements with the cubic curves have dimensions 80px x 47px. The 47 is a magic number that matches what the height that the central portion of the tab ends up being. We should define the height of the tab instead of it depending on font size.
By forming the tab from three elements, you can edit the text and the tab’s width will automatically change accordingly. However I do not know whether you may get artefacts appearing where the elements abut each other…